I have a separate audio track for a video that I shot. I lined the audio up with the video so the speaker's mouth matches the words, however, when I render the file, they go out of sync about halfway through. The sync problems happen right after a cut I made in the two files. When I watch the preview, everything looks fine. Once rendered, it starts a little out of sync and as time goes on, the video and audio get further and further out of sync. Any ideas how to trouble shoot this?

Kdenlive Version 17.04.3

I'm rendering using the presets with the program, as an MP4, one level below highest quality, in the quality slider.

Thank you!